U.S. patent number 8,509,159 [Application Number 12/014,663] was granted by the patent office on 2013-08-13 for method and system for wireless communication using out-of-band channels.
This patent grant is currently assigned to Samsung Electronics Co., Ltd.. The grantee listed for this patent is Chiu Ngo, Xiangping Qin, Huai-Rong Shao, Harkirat Singh. Invention is credited to Chiu Ngo, Xiangping Qin, Huai-Rong Shao, Harkirat Singh.
United States Patent |
8,509,159 |
Shao , et al. |
August 13, 2013 |
Method and system for wireless communication using out-of-band
channels
Abstract
A method and system for ad-hoc wireless communication using
out-of-band control channels is provided. An out-of-band control
channel is scanned to discover a wireless station. Channel
occupation information is communicated with the discovered station.
A communication channel is selected based on the occupation
information, and may be used for ad-hoc mode information
communication with the discovered station.
Inventors: |
Shao; Huai-Rong (Santa Clara,
CA), Singh; Harkirat (Santa Clara, CA), Qin;
Xiangping (San Jose, CA), Ngo; Chiu (San Francisco,
CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Shao; Huai-Rong
Singh; Harkirat
Qin; Xiangping
Ngo; Chiu |
Santa Clara
Santa Clara
San Jose
San Francisco |
CA
CA
CA
CA |
US
US
US
US |
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Assignee: |
Samsung Electronics Co., Ltd.
(Suwon, KR)
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Family
ID: |
39636144 |
Appl.
No.: |
12/014,663 |
Filed: |
January 15, 2008 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20080175197 A1 |
Jul 24, 2008 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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60881441 |
Jan 19, 2007 |
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Current U.S.
Class: |
370/329; 370/480;
370/343 |
Current CPC
Class: |
H04W
72/02 (20130101); H04W 84/18 (20130101); H04W
72/0406 (20130101); H04W 8/005 (20130101) |
Current International
Class: |
H04B
7/212 (20060101) |
Field of
Search: |
;370/329,343,480 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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10-2002-0038823 |
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May 2002 |
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KR |
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1020020038823 |
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May 2002 |
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KR |
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1020040069516 |
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Aug 2004 |
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KR |
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02067459 |
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Aug 2002 |
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WO |
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Primary Examiner: Patel; Jay P
Attorney, Agent or Firm: Sherman, Esq.; Kenneth L.
Zarrabian, Esq.; Michael Sherman & Zarrabian LLP
Parent Case Text
RELATED APPLICATION
This application claims priority from U.S. Provisional Patent
Application Ser. No. 60/881,441, filed on Jan. 19, 2007,
incorporated herein by reference.
Claims
What is claimed is:
1. A method of wireless communication, comprising: scanning an
out-of-band wireless channel to discover a wireless station;
exchanging device profiles comprising a set of device capability
information between a discovery station and a discovered partner
station over the out-of-band channel to establish association,
wherein the capability information comprises one or more of station
transmit and receive rate capability information, physical (PHY)
layer capability information and station mobility capability
information comprising a fixed station and mobile station
capability, wherein the discovery station and the discovered
partner station use the capability information of one another for
determining whether to associate for communication with one another
over an in-band wireless channel; communicating channel occupation
information with the discovered partner station; and selecting an
in-band wireless channel based on the occupation information for
information communication with the discovered partner station.
2. The method of claim 1, wherein scanning an out-of-band channel
includes detecting beacons from a wireless station.
3. The method of claim 1 wherein the capability information further
comprises power source capability information.
4. The method of claim 3, wherein the power source capability
information comprises a battery and alternating current (AC) line
capability bit field.
5. The method of claim 1, wherein communicating channel occupation
information includes communicating channel occupation information
with the discovered partner station over the out-of-band
channel.
6. The method of claim 1, wherein the channel occupation
information includes channel bandwidth availability
information.
7. The method of claim 6, wherein selecting an in-band channel
includes selecting an in-band channel based on the channel
bandwidth information, wherein the channel bandwidth information
comprises reservation and scheduling information.
8. The method of claim 1, wherein selecting an in-band channel
includes selecting an in-band communication channel based on the
occupation information for ad-hoc mode information communication
with the discovered partner station, wherein for ad-hoc mode,
stations coordinate with each other within a transmission range of
one another.
9. The method of claim 8, wherein selecting an in-band channel
includes selecting a 60 GHz frequency band communication channel
based on the occupation information for ad-hoc mode information
communication with the partner discovered station.
10. The method of claim 8, wherein ad-hoc mode further comprises
each station transmitting its own beacon on a control channel and
placing therin channel occupation information.
11. The method of claim 1, further including communicating data
with the discovered partner station over the in-band channel, while
using the out-of-band channel to exchange of control messages,
wherein the in-band channel and the out-of band channel are at
different wireless frequencies.
12. The method of claim 11 further including performing directional
data communication over the in-band channel and performing
omni-directional control message signaling communication over the
out-of-band channel.
13. The method of claim 1, wherein the out-of band channel is at a
lower frequency band than the in-band channel.
14. The method of claim 1, wherein the out-of-band channel is at a
same frequency band as the in-band channel, but at a different
frequency.
15. The method of claim 1 further including communicating beacons
on the out-of-band channel, wherein the beacons can be transmitted
anywhere in a superframe period.
16. The method of claim 1, wherein the occupation information
comprises duration of a reserved channel time block.
17. The method of claim 1, wherein scanning the out-of-band
wireless channel to discover the wireless station comprises
discovering the wireless station for a partner before selecting the
in-band wireless channel and reserving bandwidth for data
communication on the in-band channel.
18. The method of claim 17, wherein scanning the out-band wireless
channel further comprises scanning at least a beacon interval time
period for detecting peak transmission energy from other stations,
and analyzing beacons and other frames from other stations.
19. The method of claim 1, wherein discovery of the wireless
station communicating of in-band channel transmission parameters
occurs before a need for data transmission by a discovering station
arises.
20. The method of claim 1, wherein an initiator station waits to
receive in-band channel occupation information from a responder
station, thereafter, the initiator station combines received
channel occupation information with its own channel occupation
information for determining an in-band channel with sufficient
available bandwidth for communication between the initiator station
and the responder station.
21. The method of claim 1, further comprising determining whether
stations can establish association based on the capability
information communicated by a discovery station and a partner
station.
22. The method of claim 1, wherein the capability information
further comprises audio/visual and data support capability
information.
23. The method of claim 1, wherein the PHY layer capability
information further comprises an asymmetric and symmetric
capability bit field.
24. The method of claim 1, further comprising: determining by the
discovery station and the partner station to associate based on
exchanging of the profiles.
25. The method of claim 24, wherein the discovery station and the
partner station each determine capability information of one
another.
26. The method of claim 25, wherein the capability information is
indicated in a bit field that comprises one or more sub-bit fields
for indicating station transmit and receive rate capability
information, physical (PHY) layer capability information, station
mobility capability information comprising fixed station and mobile
station capability, and audio support, video support, and data
support capability.
27. The method of claim 1, wherein after discovery on the
out-of-band channel, the discovery station and the discovered
partner station transmit control packets in the out-of-band channel
for device and service discovery.
28. The method of claim 27, wherein after discovery on the
out-of-band channel, the discovery station and the discovered
partner station exchange in-band channel capability information
using convergence layer control messages.
29. A wireless communication station, comprising: a processor
coupled with: an out-of-band communication module configured for
scanning an out-of-band communication channel to discover a
wireless partner station and communicating control information over
the out-of-band channel, and exchanging device profiles between the
wireless communication station and the wireless partner station,
the profiles each comprising a set of device capability information
over the out-of-band channel for establishing association between
the wireless communication station and the wireless partner
station, wherein the capability information comprises station
transmit and receive rate capability information and station
mobility capability information comprising a fixed station and
mobile station capability bit field; an in-band communication
module configured for information communication over an in-band
communication channel; and a convergence module configured for
communicating channel occupation information with the wireless
partner station to select an in-band for in-band communication with
the wireless partner station via the in-band communication module,
wherein the wireless communication station and the wireless partner
station use the capability information of one another for
determining whether to associate for communication with one another
over a selected in-band wireless channel.
30. The wireless station of claim 29, wherein the convergence
module is further configured for scanning an out-of-band control
channel using the out-of-band communication module by detecting
beacons from a wireless station.
31. The wireless station of claim 29, wherein the capability
information further comprises station high rate channel transmit
and receive communication capability information.
32. The wireless station of claim 29, wherein the out-of-band
convergence module is further configured for communicating channel
occupation information with the wireless partner station over the
out-of-band channel.
33. The wireless station of claim 29, wherein the channel
occupation information includes channel bandwidth reservation and
scheduling information.
34. The wireless station of claim 33, wherein the convergence
module is further configured for selecting an in-band channel based
on the channel bandwidth information.
35. The wireless station of claim 29, wherein the convergence
module is further configured for selecting an in-band channel based
on the occupation information for ad-hoc mode in-band communication
with the wireless partner station.
36. The wireless station of claim 29 wherein the convergence module
is further configured for selecting a 60 GHz frequency in-band
communication channel based on the occupation information for
information communication with the wireless partner station.
37. The wireless station of claim 29, wherein the out-of-band
communication module is further configured for performing
omni-directional communication over the out-of-band channel.
38. The wireless station of claim 29, wherein the in-band
communication module is further configured for performing
directional data communication over the in-band channel.
39. The wireless station of claim 29, wherein the out-of-band
channel is at a lower frequency band than the in-band channel.
40. The wireless station of claim 29, wherein the out-of-band
channel is at a same frequency band as the in-band channel.
41. The wireless station of claim 29, wherein the out-of-band
communication module is further configured for communicating
beacons on the out-of-band channel, wherein the beacons can be
transmitted anywhere in a superframe period.
42. A program product stored on a computer useable non-transitory
medium for wireless communication, the program product comprising
program code for causing a processor of a wireless station to
perform: scanning an out-of-band wireless channel to discover a
partner wireless station; communicating channel occupation
information and exchanging device profiles comprising a set of
station capability information between the wireless station and the
partner station, wherein the station capability information
comprises station transmit and receive rate capability information
and station mobility capability information comprising a fixed
station and mobile station capability bit field; and selecting an
in-band wireless channel based on the occupation information for
information communication with the partner station, wherein the
wireless station and the partner station use the capability
information of one another for determining whether to associate for
communication with one another over a selected in-band wireless
channel.
43. The program product of claim 42 further comprising program code
for causing a processor of the wireless station to exchange
capability information with the partner station to establish
association.
44. A wireless communication system, comprising: an electronic
wireless discovering station and a wireless partner station; the
discovering station comprising: an out-of-band communication module
configured for scanning an out-of-band communication channel to
discover a partner station and communicating control information
over the out-of-band channel, and for exchanging device profiles
comprising a set of device capability information between the
discovering station and the partner station over the out-of-band
channel for establishing association with the partner station,
wherein the capability information comprises one or more of station
transmit and receive rate capability information, physical (PHY)
layer capability information and station mobility capability
information comprising fixed station and mobile station capability
bit field; an in-band communication module configured for
information communication over an in-band communication channel;
and a convergence module configured for communicating channel
occupation information with the partner station to select an
in-band channel for in-band communication with the partner station
via the in-band communication module, wherein the discovering
station and the partner station use the capability information of
one another for determining whether to associate for communication
with one another over a selected in-band wireless channel.
45. The system of claim 44, wherein the convergence module is
further configured for scanning an out-of-band control channel
using the out-of-band communication module by detecting beacons
from a wireless station to discover the partner station.
46. The system of claim 44, wherein the capability information
further comprises station high rate channel communication
capability information.
47. The system of claim 44, wherein the out-of-band convergence
module is further configured for communicating channel occupation
information with the partner station over the out-of-band
channel.
48. The system of claim 44, wherein the channel occupation
information includes channel bandwidth availability
information.
49. The system of claim 48, wherein the convergence module is
further configured for selecting an in-band channel based on the
channel bandwidth information.
50. The system of claim 44, wherein the convergence module is
further configured for selecting an in-band channel based on the
occupation information for ad-hoc mode in-band communication with
the partner station.
51. The system of claim 44, wherein the convergence module is
further configured for selecting a 60 GHz frequency in-band
communication channel based on the occupation information for
information communication with the partner station.
52. The system of claim 44, wherein the out-of-band communication
module is further configured for performing omni-directional
communication over the out-of-band channel.
53. The system of claim 44, wherein the in-band communication
module is further configured for performing directional data
communication over the in-band channel.
54. The system of claim 44, wherein the out-of-band channel is at a
lower frequency band than the in-band channel.
55. The system of claim 44, wherein the out-of-band channel is at a
same frequency band as the in-band channel.
56. The system of claim 44, wherein the out-of-band communication
module is further configured for communicating beacons on the
out-of-band channel, wherein the beacons can be transmitted
anywhere in a superframe period.
Description
FIELD OF THE INVENTION
The present invention relates to wireless communications, and in
particular to channels for wireless communications.
BACKGROUND OF THE INVENTION
Many communication systems implement infrastructure mode wireless
networking for communication via central connection points (access
points) for wireless local area network (WLAN) clients. An access
point forwards data for the wireless clients, enabling the wireless
clients to communicate with each other through the access
point.
In some applications of infrastructure mode wireless networking, a
wireless access point that functions as a coordinator uses an
in-band control channel, and stores the information of all wireless
client devices associated to it. In this case a device can send an
information request to the coordinator to obtain the in formation
of other devices within the wireless network.
Such infrastructure mode assumes all devices can periodically
receive beacons from the wireless coordinator, indicting channel
occupation. However, one or more devices may be located outside the
transmission coverage range of the coordinator. For example, if
wireless device A wishes to discover wireless device B, but one or
both of the two devices are not within reach of the wireless
coordinator, then the discovery mechanism fails.
BRIEF SUMMARY OF THE INVENTION
The present invention provides a method and system for wireless
communicates using an out-of-band channel. One embodiment involves
using an out-of-band wireless channel to facilitate information
communication on an in-band wireless channel between a pair of
wireless stations.
An implementation includes the steps of scanning an out-of-band
channel to discover a wireless station, and communicating channel
occupation information with the discovered station. Then an in-band
communication channel is selected based on the occupation
information for information communication with the discovered
station over the in-band channel. The information communication may
include ad-hoc mode communication over the in-band wireless
channel.
In one implementation, capability information is communicated with
the discovered station over the out-of-band channel to establish
association. Further, communicating channel occupation information
includes communicating channel occupation information with the
discovered station over the out-of-band channel.
These and other features, aspects and advantages of the present
invention will become understood with reference to the following
description, appended claims and accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a block diagram of a wireless network implementing
wireless communication, according to an embodiment of the present
invention.
FIG. 2 shows an example configuration for ad-hoc wireless
communication, according to the present invention.
FIG. 3 shows an example protocol architecture for wireless
communication by a wireless station in a wireless network,
according to the present invention.
FIG. 4 shows an example flowchart of a device discovery process via
an out-of-band channel for wireless communication, according to the
present invention.
FIG. 5 shows an overall flowchart of an example process for using
an out-of-band wireless channel to facilitate information
communication on an in-band wireless channel between a pair of
wireless stations, according to an embodiment of the present
invention.
In the drawings, like references refer to similar elements.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a method and system for wireless
communication using an out-of-band channel. One embodiment involves
a communication process using an out-of-band wireless channel to
facilitate information communication on an in-band wireless channel
between a pair of wireless stations. An out-of-band channel is a
first physical channel that is out-of-band relative to a second
physical channel (i.e., an in-band channel). The out-of-band
channel is at a frequency different from an in-band channel. For
example, an in-band data transmission channel may operate on a 60
GHz frequency band, whereas, an out-of-band channel may operate on
a 5 GHz or 2.4 GHz (or even another 60 GHz) frequency band. An
out-of-band frequency means a different frequency than an in-band
frequency, even if both are in the same frequency band.
In one implementation of the above communication process, an
out-of-band channel is used for control message transmissions. This
helps reduce collisions and interferences between adjacent
transmissions on an in-band channel, whereby multiple streams can
be simultaneously transmitted on the same in-band data channel
using a directional transmission scheme. In an ad-hoc mode wireless
communication process, each wireless client in a network forwards
data for other wireless clients as determined based on the network
connectivity, by using out-of-band channels for communicating
control information messages according to the present
invention.
A reservation scheme may be applied to a channel (out-of-band
channel and/or in-band channel) based on a superframe structure
including superframes separated by beacons. In a contention-free
period (CFP), time scheduling is utilized, wherein beacons provide
information about scheduled channel time blocks. Further, a
bandwidth reservation scheme is applied based on the superframe
structure, wherein beacons divide the channel time into multiple
superframes. In each superframe there are contention periods and
contention-free periods. In each CFP there are one or more
schedules, wherein each schedule includes one or more reserved
channel time blocks for transmission. The schedules represent
reserved channel time blocks, and the time periods between the
schedules are unreserved channel time blocks. The length of each
reserved channel time block is defined in a schedule for a pair of
stations. In one example, a beacon can include bandwidth allocation
information elements (IE), indicating channel occupation
information (e.g., certain duration of a channel time block is
reserved for communication).
Transmission of beacons can be placed anywhere in a superframe,
(e.g., mMaxBeaconIntervalTime period) providing flexibility for
point-to-point ad-hoc transmissions with an out-of-band channel for
control messages.
An example implementation for a 60 GHz frequency band wireless
network is described below. Such implementation is useful with
Wireless HD (WiHD) applications. Wireless HD is an industry-led
effort to define a wireless digital network interface specification
for wireless HD digital signal transmission on the 60 GHz frequency
band, e.g., for consumer electronics (CE) and other electronic
products. An example WiHD network utilizes a 60 GHz-band mmWave
technology to support a physical (PHY) layer data transmission rate
of multi-Gbps (gigabits per second), and can be used for
transmitting uncompressed high definition television (HDTV) signals
wirelessly. The present invention is useful with other wireless
communication systems as well.
FIG. 1 shows a functional block diagram of a wireless network 10
that implements ad-hoc wireless communication between N wireless
stations 12 (e.g., devices Dev1, . . . , DevN-1) on a 60 GHz
frequency band using Frequency Division Duplex (FDD) channel
access, according to an embodiment of the present invention. An
out-of-band channel 16 is used for ad-hoc mode control message
transmissions to coordinate the transmissions on the in-band data
channel 18. Transmission beacons can be placed anywhere in a
superframe on the out-of-band channel, providing flexibility for
point-to-point 60 GHz ad-hoc transmissions with an out-of-band
channel.
At higher frequency bands such as 60 GHz there is much more free
space loss than at lower frequencies such as 2 GHz or 5 GHz because
free space loss increases quadratically with the increase in the
frequency. This higher free space loss can be compensated for using
multiple antennas with more pattern directivity, while maintaining
small antenna dimensions, known as beamforming. When beamforming is
used, antenna obstruction (e.g., by an object) and mis-pointing,
may easily cause a substantial drop in received transmission power.
This may nullify the advantage of using multiple antennas.
Therefore, dynamic beamsearching and beamtracking are used to
maintain stable beamforming transmission. Beamtracking involves
monitoring the quality of beamformed transmission on a beamforming
channel, while beamsearching involves searching for new beamforming
coefficients to provide satisfactory channel quality. At higher
frequencies such as 60 GHz transmissions, directional antennas can
be used, wherein one or more directional antennas at a sender can
physically point to a receiver to compensate for higher free space
loss. Usually there is no dynamic beamsearching when directional
antennas are used, and simple antenna scanning or training can be
used instead.
In the example network 10 shown in FIG. 1 according to the present
invention, the stations 12 operate in ad-hoc transmission mode,
wherein stations coordinate with each other within the transmission
range of one another. An out-of-band omni-directional channel 16 is
used for control message signaling purposes, and a directional
in-band data channel 18 (e.g., 60 GHz) is used for data
communication. In one example, the out-of-band channel 16 can use
different technologies such as Bluetooth, WLAN, other wireless
technologies such as UWB, or even another different 60 GHz channel
(e.g., same bandwidth or narrower than channel 18). The out-of-band
channel 16 has the same coverage range as the in-band data channel
18. The data channel 18 is an asymmetric channel (e.g., 60 GHz data
transmission is for one-way transmission only). Further, there is a
default channel for control messages all of the stations but there
need not be an in-band data channel for all of the stations.
The out-of-band channel 16 is a symmetric channel and supports a
half-duplex mode. The in-band channel selection (e.g., to determine
which 60 GHz data channel to use) for data communication between
two stations is determined between the two stations (devices) by
bandwidth reservation signaling on a default out-of-band channel
(e.g., sending a bandwidth reservation request message and
obtaining a bandwidth reservation response indicating if the
bandwidth is reserved). Multiple transmissions can share the same
in-band channel simultaneously by using the directional
transmission to avoid interference.
FIG. 2 shows an example communication configuration in a network 20
including wireless stations 22 (e.g., Device A, Device B, Device C,
Device D, Device E and Device F), according to the present
invention. The stations 22 use an out-of-band channel (control
channel) 16 and an in-band channel (data transmission) such as a 60
GHz channel as shown. In this example, Device A and Device B are
involved in data communication, and Device C and Device D are
involved in data communication. If data transmission from Device A
to Device B does not interfere with data transmission from Device C
to Device D, then Device A and Device B can simultaneously use the
same in-band data channel as Device C and Device D.
FIG. 3 shows an example block diagram of an architecture 30 for a
wireless station 31 (e.g., a station 22 in FIG. 2 or a station 12
in FIG. 1). The station 31 includes an out-of-band communication
module 32 (e.g., low-rate wireless transceiver) and an in-band
communication module 33 (e.g., high-rate wireless transceiver). The
communication module 32 (control communication module) is used for
communication of control messages via an out-of-band channel 16.
The communication module 33 (data communication module) is used for
data communication via an in-band channel 18.
The station 31 can function as an initiator or a responder, wherein
a transmission initiator is a station that first initiates
transmission and can be a transmission sender or receiver. A
transmission responder is a station that responds to the
transmission initiator and can be a transmission sender or
receiver. A frame structure is used for data transmission between
wireless stations. The communication protocol can be an
infrastructure mode or an ad-hoc mode communication protocol.
For example, frame aggregation can be used in a Media Access
Control (MAC) layer and a PHY layer. The MAC layer obtains a MAC
Service Data Unit (MSDU) and attaches a MAC header thereto, in
order to construct a MAC Protocol Data Unit (MPDU), for
transmission. The MAC header includes information such as a source
address (SA) and a destination address (DA). The MPDU is a part of
a PHY Service Data Unit (PSDU) and is transferred to a PHY layer in
the transmitter to attach a PHY header (i.e., PHY preamble) thereto
to construct a PHY Protocol Data Unit (PPDU). The PHY header
includes parameters for determining a transmission scheme including
a coding/modulation scheme. Before transmission as a packet from a
transmitter to a receiver, a preamble is attached to the PPDU,
wherein the preamble can include channel estimation and
synchronization information.
The communication module 33 provides a MAC/PHY path for the data
communication over an in-band channel, and the communication module
32 provides a MAC/PHY path for control message communication over
an out-of-band channel. Specifically, the communication module 32
implements out-of-band communication for control transmission via
an antenna 32C on an out-of-band channel. The communication module
32 implements an in-band communication for transmission of
information (e.g., data, video, audio, etc.) via the antennas 33C
on an in-band channel.
The out-of-band channel is used for device discovery and
association between two stations, which allows selection of an
in-band communication channel for information transmission between
the two stations.
A convergence module 34 in the wireless station 31 implements a
process using the communication module 32 for scanning an
out-of-band channel 16 via the communication module 32 to discover
another wireless station, communicating capability information with
a discovered station to establish association, and communicating
channel occupation information with the discovered station.
Thereafter, the convergence module 34 provides selection of an
in-band communication channel 18 based on the occupation
information for information communication with the discovered
station via the communication module 33 on the in-band channel. The
information communication may include ad-hoc mode communication
over the in-band wireless channel.
As noted, the communication module 33 comprises a high-rate (HR)
module including a HR MAC/PHY path for the in-band data channel 18
(e.g., a 60 GHz frequency band). Further, the communication module
32 comprises a low-rate module including a LR MAC/PHY path for the
out-of-band channel 16 (e.g., Bluetooth, UWB or WLAN, or a
different 60 GHz band as used in the HR path).
Specifically, the communication module 32 comprises a LR MAC layer
32A and a LR PHY layer 32B, and supports omni-directional wireless
communication over the out-of-band channel 16. The communication
module 33 comprises a HR MAC layer 33A and a HR PHY layer 33B, and
supports directional (or beamformed/steered) wireless communication
on the in-band channel 18.
The convergence module 34 interfaces an application/user control
layer 35, and coordinates and synchronizes the communication
modules 32 and 33 by messaging.
The convergence module 34 includes a connection module 34A that
provides overlay connection control and management for various
channels (e.g., both LR and HR channels), by communication of
control/management information via the out-of-band control channel
16. In one example, the connection module 34A coordinates
communications through a 60 GHZ frequency band via the
communication module 33 and through a 2.4 GHz, 5 GHz or a different
60 GHz frequency band via the communication module 32.
The convergence module 34 further includes an adaptation module 34B
that provides information adaptation for communication via the
in-band channel 18. In one example, the adaptation module 34B
provides video stream/data adaptation for communication via the
in-band channel, wherein such adaptation includes pixel
partitioning, aggregation/acknowledgment, fast format/link
adaptation, transmission power control, etc.
As noted, the LR PHY/MAC layer implemented by the communication
module 32 is mainly used for control message exchange between
stations on the out-of-band channel 16. An example is when
initially a first station 31 powers on or resumes operation the
convergence layer 34 uses the communication module 32 to
communicate control messages on the out-of-band channel to discover
and associate with other stations. Upon successful discovery and
association, an in-band channel is established by bandwidth
reservation for communication (e.g., ad-hoc mode) on the selected
in-band channel between the first station and another station via
the HR PHY/MAC layer of the communication module 32. In addition,
when the in-band channel is established, control message may be
transmitted on the out-of-band channel for facilitating
communication on the in-band channel by the two stations.
An example communication scenario is now described. FIG. 3 shows
three logical communication paths in the station 31. A first path
represents a high-rate data communication path 1 which can carry
information (e.g., data, high-rate uncompressed video/audio, etc.).
A second path represents a high-rate communication path 2 which can
carry control messages after the in-band channel has been
established between two wireless stations. A third path represents
a low-rate communication path 3 which can carry control/management
messages on the out-of-band channel, such as before the in-band
channel is established between two stations.
FIG. 4 shows a flowchart of the steps for an example device
discovery process 40 on an out-of-band channel implemented by the
architecture 30 in FIG. 3, according to the present invention.
Every station transmits its own beacon on a control channel, and
places therein the channel occupation information that the station
is aware of. Referring to FIG. 4, a discovering wireless station
(station) scans the default out-band-channel channel to discover a
partner wireless station (partner), before selecting an in-band
channel (e.g., selecting a 60 GHz channel) and reserving bandwidth
for data communication therebetween on the in-band channel. The
process 40 includes the following steps: Step 41: A station powers
on or resumes operation. Step 42: The station scans the default
out-of-band channel (control channel) during a
mMaxBeaconIntervalTime period for a beacon frame from a partner.
Step 43: It is determined if the station received a beacon from the
partner over the out-of-band channel. If yes, go to step 49,
otherwise proceed to step 44. Step 44: It is determined if the
station is a transmission initiator. If yes, go to step 48,
otherwise proceed to step 45. Step 45: At free control channel time
periods, the station randomly transmits its own beacon with a
device discovery information element (IE) on the out-of-band
channel. Step 46: It is determined if the station received any
beacons on the out-of-band channel from the partner. If yes, go to
step 49, otherwise proceed to step 47. Step 47: It is determined if
a reply period timeout (e.g., mMaxReplyingBeaconTimeout) has
occurred. If not, go back to step 46, otherwise proceed to step 51.
Step 48: It is determined if a reply period timeout (e.g.,
mMaxReplyingBeaconTimeout) has occurred. If yes, proceed to step
51, otherwise go back to step 42. Step 49: The stations transmit
beacon(s) on the out-of-band channel in reply to the partner. Step
50: Completion of a successful partner discovery. Stop. Step 51:
Report the partner discovery failure, for this period, to the
application/user. Stop.
In one example scenario according to the process 40 implemented by
the connection module 34A of the convergence module 34A, a station
31 powers on or resumes from stand-by, and using its communication
module 32 scans the default out-of-band channel for at least a
beacon interval time period, to detect peak transmission energy
from other stations, and analyze beacons and other frames from a
(potential) partner it wishes to discover. If the station is the
initiator for communication, but cannot receive any beacons from
the partner, then the station sends out its own beacon with a
device discovery IE on the out-of-band channel. If the station
receives a reply beacon from the partner on the out-of-band
channel, then the station and partner successfully discover each
other.
However, if the station is a transmission responder, but cannot
receive any frames from the partner, then the station keeps
scanning the out-of-band channel for beacons from the partner
(i.e., the transmission initiator). If the station receives a
beacon sent from the partner, the station replies with a beacon as
soon as possible over a free channel time block on the out-of-band
channel (the station and partner successfully discover each
other).
In the above discovery process, by only allowing the transmission
initiator to send out beacons at the discovery stage, the
probability of collision between the initiator and the responder
may be reduced.
After discovery on the out-of-band channel is successfully
completed, the station and the partner transmit control packets on
the out-of-band channel for further device and service discovery,
and exchange in-band channel capability using convergence layer
control messages 34C implemented by the communication module 34A of
the convergence module 34. The connection module 34A manages
scheduling and synchronization, device and service discovery
functions, association and authentication functions, and bandwidth
reservation.
After a station discovers a partner, then during an association
process the station and the partner exchange capability information
via the convergence module, on an out-of-band channel (e.g., LR
channel 16), for establishing an in-band data channel (e.g., HR
channel 18). The control messages 34C via the convergence module
carry the capability information between the station and the
partner on the out-of-band channel. The station and partner set the
capability information fields in the control messages 34C and
exchange that information on the out-of-band channel. The control
messages can be placed in convergence layer beacons or other
control message formats, and transmitted by the communication
module 32 of the involved stations on the out-of-band channel. The
station and partner then check such capability information to
determine if they can appropriately communicate over an in-band
channel.
Such capability information includes device profiles defining the
set of PHY (asymmetric or symmetric) capability, high-rate data
capability, and other capabilities such as fixed or mobile, AC line
or battery powered, Audio/Visual (AV) and/or data support, etc.,
for a station. Table 1 below shows an example station capability
field exchanged during the association process:
TABLE-US-00001 TABLE 1 Capability Field Bits: 1 1 1 2 HR HR Battery
Support Transmit Receive or line AV or powered Data
In one example, if a subfield in the capability field above is set,
that indicates the station has the capability. A "Support AV or
Data" subfield is shown in Table 2 below:
TABLE-US-00002 TABLE 2 Audio/Visual (AV) or Data Subfield Value
Meaning 00 Support Data 01 Support AV 10 Support both Data and AV
11 Reserved
The capability information is used by the stations to determine if
they can associate for communication on an in-band channel.
After discovery and association, the discovering station and the
partner station (e.g., the initiator and the responder), determine
capabilities of one another. For example, a 60 GHz in-band channel
can be selected for communication if both the station and the
partner have the capability to communication over such as in-band
channel (i.e., both the station and the partner include 60 GHz
transceivers or are 60 GHz capable stations).
If both the station and the partner have such in-band communication
capability, then they perform in-band communication channel
selection (e.g., to determine which 60 GHz data channel to use) and
bandwidth reservation, by signaling on the default out-of-band
channel. In one example, after successful discovery and
association, the initiator and responder select an in-band
communication channel from m channels in the 60 GHz frequency band,
and reserve bandwidth on the selected in-band channel for
communication therebetween. For example, if each data channel is 2
GHz in-band, then m<4 in most regions of the world. An example
in-band channel selection process is described below.
In ad-hoc mode, every station transmits its own beacon on a control
channel, and places therein the channel occupation information that
the station is aware of. For example, convergence layer beacons or
other control message formats, carrying channel occupation
information are transmitted via the convergence module of each
station over an out-of-band channel. Such channel occupation
information includes information indicating if an in-band channel
is in use, and by which stations (e.g., in-band channel bandwidth
reservation information, in-band channel time scheduling
information, etc.).
The initiator and the responder analyze the beacons received on the
same default out-of-band channel (e.g., an LR channel), to obtain
channel occupation information for each in-band channel (HR
channel, e.g., a 60 GHz wireless channel). The responder transmits
an in-band channel occupation information notification frame to the
initiator over the control channel, to report the in-band channel
occupation information obtained from the received beacons. The
initiator receives the in-band channel occupation information and
combines the channel occupation information for itself and the
responder, to select an in-band channel for communication.
Specifically, when an initiator and a responder need to communicate
on an in-band channel, the initiator waits to receive in-band
channel occupation information from the responder. Thereafter, the
initiator combines the received channel occupation information with
its own channel occupation information, which allows the initiator
to determine which in-band channel has sufficient available
bandwidth for communication between the initiator and the
responder.
In one example, the initiator attempts to select a free 60 GHz
in-band channel for transmission. If no free 60 GHz channel is
available, the initiator and responder continue monitoring
convergence layer beacons carrying channel occupation information,
until such an in-band channel becomes available. The initiator and
the responder then broadcast convergence layer ad-hoc mode beacons
over the out-of-band channel via the convergence module, for
bandwidth reservation and data communication over a selected
in-band 60 GHz channel. Said ad-hoc beacons may include information
similar to that in e.g., an IEEE 802.15.3 beacon or WiHD beacon,
such as channel time scheduling information. As such, in this
example the default out-of-band channel is to facilitate discovery,
association and in-band channel selection for all 60 GHz capable
stations.
Referring to an example data channel selection process 60 in FIG. 5
for an initiator and responder, after successful station discovery
(step 61) and association (step 62) between the initiator and
responder as described above, it is determined if the out-of-band
channel (e.g., LR channel 16) is used by the initiator and
responder (step 63). If yes, then the in-band channel (e.g., HR
channel 18) occupation information is obtained for each in-band
channel from convergence layer beacons received on the default
out-of-band channel (step 65). Using the in-band channel occupation
information, an in-band channel is selected for data transmission
between the initiator and the responder (step 66). Then,
directional transmission including typical training or beamsteering
is performed on the in-band (HR) channel between the initiator and
the responder. Directional data transmission is then performed at
reserved times on the selected in-band channel based on the
training and beamsteering information (step 68).
In step 63, if the initiator and responder use different
out-of-band control channels (such as when multiple LR control
channels are available for use with HR stations (e.g., 60 GHz data
channel capable devices)), then the initiator and responder search
for convergence layer beacons at all such out-of-band channels
(step 64), to collect in-band channel allocation information. After
searching, if an in-band channel is available for both the
initiator and responder, the initiator and responder can reserve
the in-band channel using data channel bandwidth reservation
signaling (e.g., control messages 34 on an out-of-band channels via
the convergence module 34). After reserving the in-band channel,
the initiator and responder broadcast convergence layer beacons
over an out-of-band channel to facilitate communication on the
in-band channel (such beacons include information similar to that
in e.g., an IEEE 802.15.3 beacon or WiHD beacon, such as channel
time scheduling information). For example, a broadcast convergence
layer ad-hoc mode beacon can be similar to a typical beacon,
exchanged via the convergence module 34 at each of the initiator
and responder.
In one example operation of the station 31, initially the
communication module 33 for in-band (HR) communication is off and
the communication module 32 for out-of-band (LR) communication is
on. The MAC LR of the communication module 32 attempts to
associate/find other stations on the out-of-band channel, and
exchanges capacity/capability information using the convergence
module on the out-of-band channel, to determine if based on the
exchanged information another station has in-band (HR)
communication capability for association (e.g., not all
stations/devices 12 in FIG. 1 are required to have both LR and HR
communication capability (e.g., DevN-1), but all stations have LR
communication capability). Upon successful discovery and
association between two stations, then the convergence module in
each station turns on the respecting communication module 33
therein for in-band channel communications.
As such, in FIG. 5, steps 61 (i.e., steps 42 and 45 in FIG. 4), 62
and 64 are performed using the out-of-band channel. Then, upon
successful discovery, the connection module 34A in each station
handles in-band communication and performs steps 65, 66, 67 and 68.
The adaptation module 34B deals with data transmission rates based
on in-band channel conditions.
If a reservation-based channel access scheme is used, then a
station can determine out-of-band channel occupation by detecting
whether a channel is available through reading beacons which
provide channel reservation information. If a contention-based
channel access scheme is used, a station can determine whether a
channel is available by sensing the channel through energy
detection. A similar approach is used for detecting in-band channel
occupation.
When a fast connection is required by users and applications, a
first wireless station can discover other wireless stations and
determine in-band channel transmission parameters before a need for
data transmission by the first station arises. This is different
from the case when a first station needs to communicate with
another station, and at that time begins discovery and negotiates
HR transmission/receiving parameters.
In order to discover other wireless stations and determine in-band
channel transmission parameters before a need for data transmission
arises, the first station implements signaling on the out-of-band
channel. Through such signaling, the first station discovers
potential stations (partners) for communication and determines
in-band channel transmission configuration parameters. This may
include determining a need for bandwidth reservation for
communication over the in-band channel in addition to determining
in-band channel transmission parameters. Further, the first station
retains the setting parameters after a transmission completes, for
re-establishing an HR link later. Such an HR link re-establishing
process may allow a station and a partner to quickly re-establish
in-band channel connections based on information from a previous
in-band link between them.
An example application involves a case where multiple source
stations can transmit streams to one sink station, at different
times. For instance, in a conference room, multiple laptop
computers can wirelessly transmit data streams to a projector
device over an in-band channel in a round-robin fashion, at
different times. Another example involves multiple devices in a
living room, such as a set top box and a DVD player, which
wirelessly transmits data/video streams to a TV over the data
channel, at different times.
As is known to those skilled in the art, the aforementioned example
architectures described above, according to the present invention,
can be implemented in many ways, such as program instructions for
execution by a processor, as logic circuits, as an application
specific integrated circuit, as firmware, etc. For example, the
convergence module 34 can be implemented as a software or firmware
application, a computer-implemented method, a program product
stored on a computer useable medium, for execution on a processor
(e.g., CPU, microcontroller) in a wireless station. The present
invention has been described in considerable detail with reference
to certain preferred versions thereof; however, other versions are
possible. Therefore, the spirit and scope of the appended claims
should not be limited to the description of the preferred versions
contained herein.
* * * * *